Whats wrong with my build?
TECH Enthusiast
Joined: Dec 2005
Posts: 530
Likes: 0
From: Owasso,Ok/Honolulu, HI
I'm not sure. My programmer doesn't show IDC but its suppose to show injector pulse width. I just can't find it. I have to get it tuned when I get the injectors installed so I'm just going to get it dyno tuned and I'll let you know how it goes. I really appreciate your help!
Well guys, I took my car to Diablo Formula Racing today. He does street tuning with hp tuners and a wideband. Checked my tune with stock injectors still in the car. The stock injectors were at 100% IDC with a 12.8-13.2 Afr at WOT. He went ahead and installed the 42# injectors and retuned it with the new injectors. Really don't think the stock injectors were the problem. For whatever reason I guess the cars is a turd. It is what it is for now. I may look at upgrading my intake in the spring or trading it in on a new 5.0! LOL
Last edited by td1168; Sep 29, 2013 at 07:03 PM.
Staging Lane
Joined: Jan 2008
Posts: 53
Likes: 1
This is funny to me only because I had this same exact build. After 4 tunes and spending a lot of money on this and that I sold the car. But it still bother me why this car did not make any power, so I got on the phone and talk to a lot of differt shop and no one could come up with a answer. So I went to a old friend and engine builder and we ran some number and found out with the 5.3 2.5 heads and heads gasket I ran the compression of my motor was like 9.71. So you might want to look into this I hope I was a help
TECH Enthusiast
Joined: Dec 2005
Posts: 530
Likes: 0
From: Owasso,Ok/Honolulu, HI
Hmmm that is odd. I kinda feel bad now because I couldn't think of anything else it could be. If your compression is down under 10:1 then I could see that being an issue as well.
What size is your combustion chamber and gasket for the heads?
What size is your combustion chamber and gasket for the heads?
I went with the 3.908 mahle power pak pistons with the 4cc valve reliefs so I could run the PRC Stage 2.5 5.3 heads with the ms4. I cc'ed the combustion chambers and they are 59cc. Head gasket is .054" thick. My pistons were setting up out of the bores .008". I calculated around 10.75:1.
I'm willing to bet those heads would make more power with a smaller cam. A few years back I had those same heads on my tired SBE LS1 with a 230/236 cam and made 447whp/415tq. The MS4 is more of a max effort cam only style cam. As weird as it may sound, a stock cube LS1 with an MS4 cam would most likely run better with stock heads than it would with big ported heads.
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Have you done a compression test?correct preload on the lifters?is the throttlebody opening up all the way?(last part sounds dumb,but its happened before).
Need to check all the basics..
Need to check all the basics..
I did check the throttle body. It is opening all the way. I did a compression test tonite and all the cylinders carry between 180 and 190 psi. I did the compression test with the engine cold. Still I think if I had a cylinder down I would see a variation. My lifter preload is .075." I did notice when I pulled the spark plugs that 1, 3, 6, and 8 are burning tan colored. 2, 4, 5, and 7 are a fluffy black like they are running rich. What would cause uneven burns like this?
But that would have nothing to do with the power being where it is.
My power peaks at 6000 rpm's and my torque peaks at 4500 rpm's. My numbers are 385/367
Attachment 420372
Attachment 420372
I've thought that that is the only other thing that could be wrong. I installed the cam straight up(dot to dot) when I rebuilt the engine. The cam had "MS4" and "111.5" stenciled on the back of it. I'm going to wait and see if some other guys comment on this. Thanks a lot for your help gtocool1! I really appreciate everyones time that has commented. Eventually we'll get this figured out and I will definitely let you guys know the outcome.
I've thought that that is the only other thing that could be wrong. I installed the cam straight up(dot to dot) when I rebuilt the engine. The cam had "MS4" and "111.5" stenciled on the back of it. I'm going to wait and see if some other guys comment on this. Thanks a lot for your help gtocool1! I really appreciate everyones time that has commented. Eventually we'll get this figured out and I will definitely let you guys know the outcome.
Guess I have to put all this on the back burner. I had the car retuned with 42# injectors last Saturday and now the car starts missing when it gets hot and runs like ****! I just assumed one of the new injectors went bad and replaced it with a new one. I should have left well enough alone! I've never had an issue with the car missing or reliability till now! I'll be starting a new thread!